Coil component

This application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2021/032850, filed on Sep. 7, 2021, which claims the benefit of Japanese Application No. 2020-163223, filed on Sep. 29, 2020, the entire contents of each are hereby incorporated by reference.

The present invention relates to a coil component and, more particularly, to a surface-mount type coil component having a structure in which a plurality of conductor layers each including a coil conductor pattern and an electrode pattern and a plurality of interlayer insulating layers are alternately stacked.

Patent Document 1 describes a surface-mount type coil component having a structure in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately stacked. In the coil component described in Patent Document 1, a plating applied to the externally exposed surface of an electrode pattern is used as an external terminal.

However, high density mounting of the coil component described in Patent Document 1 may cause a short-circuit failure due to the flow of a solder in an unintended direction.

It is therefore an object of the present invention to prevent a short-circuit failure by controlling the flow of a solder in a surface-mount type coil component having a structure in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately stacked.

A coil component according to the present invention includes a coil part in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately stacked. The plurality of conductor layers each have a coil conductor pattern embedded in the coil part and an electrode pattern exposed from the coil part. The plurality of electrode patterns are connected to one another through a plurality of via conductors penetrating the plurality of interlayer insulating layers. One or more interlayer insulating layers protrude from the surfaces of the plurality of electrode patterns at a part between the plurality of electrode patterns.

According to the present invention, the interlayer insulating layer protrudes from the surface of the electrode pattern, so that the flow of a solder in the stacking direction can be suppressed by the protruding part of the interlayer insulating layer. This makes it possible to prevent a short-circuit failure due to the flow of a solder in the stacking direction.

The coil component according to the present invention may further include first and second magnetic layers sandwiching the coil part in the stacking direction. This makes it possible to obtain larger inductance. In this case, the surface of each of the plurality of electrode patterns may be recessed from the surfaces of the first and second magnetic layers. This makes a solder less likely to flow to the surfaces of the first and second magnetic layers.

In the present invention, the surface of each of the plurality of electrode patterns may be covered with an external terminal, and the protruding amount of each of the plurality of interlayer insulating layers from the surface of the eternal terminal may be set to 1 μm to 5 μm. This makes it possible to sufficiently control the flow of a solder while suppressing an increase in manufacturing cost.

In the present invention, the surfaces of the plurality of electrode patterns and protruding parts of the plurality of interlayer insulating layers may be covered with a conductive paste. This makes it possible to enlarge contact area with a solder at the time of mounting.

As described above, according to the present invention, it is possible to prevent a short-circuit failure due to unintended flow of a solder in a surface-mount type coil component having a structure in which a plurality of conductor layers and a plurality of interlayer insulating layers are alternately stacked.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

is a perspective view illustrating the outer appearance of a coil componentaccording to a preferred embodiment of the present invention.

The coil componentaccording to the present embodiment is a surface-mount type chip component and includes, as illustrated in, first and second magnetic layers,and a coil partsandwiched between the first and second magnetic layersand. Although the configuration of the coil partwill be described later, in the present embodiment, four conductor layers each having a coil conductor pattern are stacked to form one coil. One end of the coil is connected to a first external terminal E, and the other end thereof is connected to a second external terminal E.

The magnetic layersandare each a composite member made of resin containing magnetic powder such as ferrite powder or magnetic metal powder and constitute a magnetic path for magnetic flux generated by making current flow in the coil. When magnetic metal powder is used as the magnetic powder, a permalloy-based material is preferably used. Further, the resin is preferably epoxy resin in the form of liquid or powder. However, it is not essential to constitute the magnetic layersandusing a composite member in the present invention and, for example, a substrate made of a magnetic material such as sintered ferrite may be used as the magnetic layer.

Unlike a common multilayer coil component, the coil componentaccording to the present embodiment is vertically mounted such that the z-direction (stacking direction) is parallel to a circuit board. Specifically, a surface Sconstituting the xz plane is used as a mounting surface. The surface Shas the first and second external terminals Eand E. The first external terminal Eis connected with one end of the coil formed in the coil part, and the second external terminal Eis connected with the other end of the coil formed in the coil part.

As illustrated in, the first external terminal Eis continuously formed from the surface Sto a surface Sconstituting the yz plane, and the second external terminal Eis continuously formed from the surface Sto a surface Sconstituting the yz plane. Although details will be described later, the external terminals Eand Eare each constituted by a laminated film of nickel (Ni) and tin (Sn) formed on the exposed surface of each of electrode patterns included in the coil part. The exposed surface of each of the electrode patterns is not a so-called solid pattern, but an interlayer insulating layer protrudes from between electrode patterns adjacent in the z-direction. That is, the external terminals Eand Eare formed avoiding the protruding parts of the interlayer insulating layers.

are plan views illustrating respectively structures of the surfaces Sto Sof the coil component.

As illustrated in, the first external terminal Ehas first to fourth parts Eto Eeach formed on the surfaces Sand Sand extending in the x- or y-direction and a fifth part Econnecting the first to fourth parts Eto E. Interlayer insulating layerstoprotrude at a part between the first to fourth parts Eto Eexcept for an area where the fifth part Eexists. Further, as illustrated in, the second external terminal Ehas first to fourth parts Eto Eeach formed on the surfaces Sand Sand extending in the x- or y-direction and a fifth part Econnecting the first to fourth parts Eto E. The interlayer insulating layerstoprotrude at a part between the first to fourth parts Eto Eexcept for an area where the fifth part Eexists.

The protrusion of the interlayer insulating layerstois generated by a recess of each of the external terminals Eand E. That is, the surface of the external terminal E(E) is recessed from the surfaces of the magnetic layersand, while the protruding parts of the interlayer insulating layerstoare substantially flush with the surfaces of the magnetic layersand. As a result, the interlayer insulating layerstoeach protrude from the surface of the external terminal E(E) by a level difference between the surface of the external terminal E(E) and the surfaces of the magnetic layersand. The protruding amount of each of the interlayer insulating layerstofrom the surface of the external terminal E(E) is preferably set to 1 μm to 5 μm. When the protruding amount is less than 1 μm, effects to be described later cannot be obtained sufficiently. On the other hand, in order to make the interlayer insulating layerstoprotrude by more than 5 μm, it is necessary to perform etching to be described later for a long period of time, which increases manufacturing cost and may deteriorate reliability due to etching damage.

Further, a part of the surface of the coil partsandwiched between the magnetic layersandthat is covered with the external terminals Eand Eand that does not have the interlayer insulating layerstois constituted by a magnetic member. The magnetic memberplays a role of magnetically connecting the magnetic layersand.

is a side view illustrating a state where the coil componentaccording to the present embodiment is mounted on a circuit board, which is viewed in the stacking direction.

As illustrated in, the coil componentaccording to the present embodiment is vertically mounted on the circuit board. Specifically, the coil componentis mounted such that the surface Sof the coil partfaces the mounting surface of the circuit board, that is, the z-direction (stacking direction) surface of the coil componentis parallel to the mounting surface of the circuit board.

Land patternsandare provided on the circuit boardand are connected respectively with the external terminals Eand Eof the coil component. Electrical and mechanical connection between the land patternsandand the external terminals Eand Eare made by a solder. A fillet of the solderis formed on a part of the external terminal E(E) that is formed on the surface S(S) of the coil part.

In the present embodiment, the surface of each of the external terminals Eand Eis recessed from the surfaces of the magnetic layersand, which forms a level difference to make the solderless likely to spread on the surfaces of the magnetic layersand. In addition, the interlayer insulating layerstoprotrude from the surface of each of the external terminals Eand E, so that the flow of the solderin the z-direction is suppressed. That is, the protruding part of each of the interlayer insulating layerstoextends in the x-direction on the surface Sof the coil partand extends in the y-direction on the surfaces Sand Sof the coil part, so that it is possible to suppress the flow of the solderin the z-direction without hindering the flow of the solderin the x- and y-directions. Thus, even when the coil componentis mounted in high density on the surface of the circuit board, it is possible to prevent a short-circuit failure due to unintended flow of the solder.

Such a level difference can be obtained by singulating the coil componentby dicing and then etching, with cleaning solution, the surfaces of the electrode patternstoandtoexposed to the dicing surface. After that, the external terminals Eand Eare formed by barrel plating while preventing them from going beyond the protrusion of the interlayer insulating layersto, whereby the coil componentaccording to the present embodiment is completed.

is a cross-sectional view of the coil componentaccording to the present embodiment.

As illustrated in, the coil partincluded in the coil componentis sandwiched between the two magnetic layersandand has the interlayer insulating layerstoand conductor layerstowhich are alternately stacked. The conductor layerstoare connected to one another through holes formed respectively in the interlayer insulating layerstoto constitute a coil. The inner diameter portion of the coil is filled with the magnetic membermade of the same material as the magnetic layer. The interlayer insulating layerstoare made of, e.g., resin, and a nonmagnetic material is used for at least the interlayer insulating layersto. A magnetic material may be used for the lowermost interlayer insulating layerand the uppermost interlayer insulating layer.

The conductor layeris the first conductor layer formed on the upper surface of the magnetic layerthrough the interlayer insulating layer. The conductor layerhas a coil conductor pattern Cspirally wound in two turns and two electrode patternsand. The electrode patternis connected to one end of the coil conductor pattern C, while the electrode patternis provided independently of the coil conductor pattern C. The coil conductor pattern Cis embedded in the coil part. The electrode patternis exposed from the coil part, and the first part Eof the external terminal Eis formed on the surface of the electrode pattern. The electrode patternis exposed from the coil part, and the first part Eof the external terminal Eis formed on the surface of the electrode pattern.

The conductor layeris the second conductor layer formed on the upper surface of the conductor layerthrough the interlayer insulating layer. The conductor layerhas a coil conductor pattern Cspirally wound in two turns and two electrode patternsand. Both the electrode patternsandare provided independently of the coil conductor pattern C. The coil conductor pattern Cis embedded in the coil part. The electrode patternis exposed from the coil part, and the second part Eof the external terminal Eis formed on the surface of the electrode pattern. The electrode patternis exposed from the coil part, and the second part Eof the external terminal Eis formed on the surface of the electrode pattern.

The conductor layeris the third conductor layer formed on the upper surface of the conductor layerthrough the interlayer insulating layer. The conductor layerhas a coil conductor pattern Cspirally wound in two turns and two electrode patternsand. Both the electrode patternsandare provided independently of the coil conductor pattern C. The coil conductor pattern Cis embedded in the coil part. The electrode patternis exposed from the coil part, and the third part Eof the external terminal Eis formed on the surface of the electrode pattern. The electrode patternis exposed from the coil part, and the third part Eof the external terminal Eis formed on the surface of the electrode pattern.

The conductor layeris the fourth conductor layer formed on the upper surface of the conductor layerthrough the interlayer insulating layer. The conductor layerhas a coil conductor pattern Cspirally wound in two turns and two electrode patternsand. The electrode patternis connected to one end of the coil conductor pattern C, while the electrode patternis provided independently of the coil conductor pattern C. The coil conductor pattern Cis embedded in the coil part. The electrode patternis exposed from the coil part, and the fourth part Eof the external terminal Eis formed on the surface of the electrode pattern. The electrode patternis exposed from the coil part, and the fourth part Eof the external terminal Eis formed on the surface of the electrode pattern.

The coil conductor patterns Cand Care connected to each other through a via conductor penetrating the interlayer insulating layer, the coil conductor patterns Cand Care connected to each other through a via conductor penetrating the interlayer insulating layer, and the coil conductor patterns Cand Care connected to each other through a via conductor penetrating the interlayer insulating layer. As a result, a coil of eight turns is formed by the coil conductor patterns Cto C, and one end thereof is connected to the first part Eof the external terminal E, and the other end thereof is connected to the fourth part Eof the external terminal E.

The electrode patternstoare connected to one another through via conductors Vto Vpenetrating respectively the interlayer insulating layersto. Similarly, the electrode patternstoare connected to one another through via conductors Vto Vpenetrating respectively the interlayer insulating layersto. As viewed in the stacking direction, the via conductors Vto Vare formed at mutually different positions, and the via conductors Vto Vare also formed at mutually different positions.

In the cross section illustrated in, the via conductor Vis exposed from the coil part, whereby the fifth part Ely of the external terminal Eis formed on the surface of the via conductor V. On the other hand, in the cross section illustrated in, the via conductors Vand Vare not exposed from the coil part, whereby the interlayer insulating layersandpositioned respectively between the electrode patternsandand between the electrode patternsandpartly protrude from the coil part. Similarly, in the cross section illustrated in, the via conductor Vis exposed from the coil part, whereby the fifth part Eof the external terminal Eis formed on the surface of the via conductor V. On the other hand, in the cross section illustrated in, the via conductors Vand Vare not exposed from the coil part, whereby the interlayer insulating layersandpositioned respectively between the electrode patternsandand between the electrode patternsandpartly protrude from the coil part.

As described above, the external terminals Eand Eare formed respectively on the surfaces of the electrode patternstoexposed from the coil partand on the surfaces of the electrode patternstoexposed from the coil partso as to avoid the protruding parts of the interlayer insulating layersto. It follows that the protruding parts of the interlayer insulating layerstoare exposed without being covered with the external terminals Eand E. This makes it possible to control the flow of the solderat the time of mounting, as described above.

The surfaces of the conductor layerstomay sometimes have a recess at portions where the via conductors Vto Vare formed. However, in the present embodiment, as viewed in the stacking direction, the via conductors Vto Vare formed at mutually different positions, and the via conductors Vto Vare also formed at mutually different positions, so that the recess formed on the surface of each of the conductor layerstois not accumulated. This makes it possible to maintain high flatness.

Further, in the present embodiment, the via conductors Vand Vare provided at symmetric positions with respect to the center of the coil part, the via conductors Vand Vare provided at symmetric positions with respect to the center of the coil part, and the via conductors Vand Vare provided at symmetric positions with respect to the center of the coil part. This facilitates pattern design of the conductor layerstoand interlayer insulating layersto.

As described above, in the coil componentaccording to the present embodiment, the surface of each of the external terminals Eand Eis recessed from the surfaces of the magnetic layersand, and the interlayer insulating layerstoeach protrude from the surfaces of the external terminals Eand E, so that it is possible to control the flow of the solderwhen the coil componentis mounted on the circuit board. This makes it possible to prevent a short-circuit failure due to unintended flow of the solder.

is a perspective view illustrating the outer appearance of a coil componentA according to a first modification.is a side view of the coil componentA.

The coil componentA illustrated indiffers from the coil componentaccording to the above embodiment in that electrodesandare provided on the surface Sof the coil componentA so as to contact the external terminals Eand E, respectively. The electrodesandare each made of conductive paste such as nano-silver paste or nano-copper paste, and the surface thereof is covered with a laminated film of nickel (Ni) and tin (Sn) for maintaining wettability with respect to a solder. Adding the thus configured electrodesandcan enlarge contact area with a solder. In addition, the interlayer insulating layerstoeach protrude from the surfaces of the external terminals Eand E, so that the electrodesandeach bite into the protruding parts of the interlayer insulating layersto. That is, the concavo-convex surface due to the protrusion of the interlayer insulating layerstois covered with the electrodesand. This enhances fixing strength of the electrodesand.

is a perspective view illustrating the outer appearance of a coil componentB according to a second modification.is a side view of the coil componentB.

The coil componentB illustrated indiffers from the coil componentA according to the first modification in that the electrodesandeach cover not only the surface Sbut also part of the surfaces Sand S. The surfaces Sand Sare the xy surfaces positioned on the opposite sides. When the surfaces Sand Sare thus each partly covered with the electrodesand, contact area with a solder is further enlarged, and fixing strength of the electrodesandis further enhanced.

is a perspective view illustrating the outer appearance of a coil componentC according to a third modification.is a side view of the coil componentC.

The coil componentC illustrated indiffers from the coil componentB according to the second modification in that the electrodepartly covers the external terminal Eexposed to the surface Sand the electrodepartly covers the external terminal Eexposed to the surface S. When a part of the external terminal Ethat is exposed to the surface Sand a part of the external terminal Ethat is exposed to the surface Sare covered with the electrodesand, respectively, contact area with a solder is still further enlarged, and fixing strength of the electrodesandis still further enhanced. Thus, when the electrodesandare added, the electrodesandeach most preferably cover the four surfaces of the coil componentC as exemplified by the coil componentC according to the third modification.

While the preferred embodiment of the present disclosure has been described, the present disclosure is not limited to the above embodiment, and various modifications may be made within the scope of the present disclosure, and all such modifications are included in the present disclosure.

For example, although the coil partincludes the four conductor layerstoin the above embodiment, the number of the conductor layers is not limited to this in the present invention. Further, the number of turns of the coil conductor pattern formed in each conductor layer is not particularly limited to a specific number.